Liquid storage tank



March 26, 1968 L. M. HERFF LIQUID STORAGE TANK Filed Oct. 10, 1966 F .F m 2 5 Wm TH M h n VM 2 4 a U a 2 4 9 L /H 6 2 n. M I y 8. a 2 u 8 2 1 H M 3 z v M H/ L 9 H 2 H 2 a H A 2 H m 6 6 0 0 M 3 3 M H w. n 2 4 6 A 2 v 2 2 4. 6 1, i i r r I i M. a 8

A t romey Patented Mar. 26, 1968 3,374,916 LIQUID STORAGE TANK Louis M. Herlf, Penn Hills Township, Allegheny County,

Pa., assignor to United States Steel Corporation, a corporation of Delaware Filed Oct. 10, 1966, Ser. No. 585,685 6 Claims. (Cl. 220-) This invention relates to the construction of large tanks that are used for storing liquids, such as oil, milk, or water, during their transport over highways or railroads.

An object of my invention is to provide a transport tank construction that has improved strength, yet is lightweight and easy to assemble. In addition, my invention also solves a particularly troublesome problem caused by the inertia of a large mass of liquid inside a transport tank that is decelerating. During deceleration of the tank, the liquid inside is thrown against the front end plate of the tank, causing great stress on this plate and the weld which secures the plate to the other walls of the tank.

One method of reducing the stress on the end plate of the tank during deceleration has been to install intermediate plates or bulkheads inside the tank to divide the mass of liquid into smaller parts. Thus, each bulkhead or end plate receives only a part of the total force which the end plate would receive were it not [for the bulkheads. While intermediate bulkheads do help to solve this stress problem, they alone are not satisfactory where a large mass of liquid is to be carried. This is due to the large number of bulkheads that are needed to withstand adequately the inertial force ofthe liquid, and the weight of these bulkheads themselves causes a problem. The total weight of the tank with the bulkheads is extremely heavy in proportion to the load that it is able to carry.

With my invention, the number of bulkheads needed for a transport tank is reduced by the employment of a series of lightweight baflie elements, which are placed to create turbulence in the liquid cargo and absorb the inertial force of the liquid in the tank. In addition, these bafile elements are part of a novel, lightweight structure which greatly strengthens the entire tank without a substantial increase in weight.

Other ob ects and advantages of my invention will ap pear more readily from the following description of my invention and the attached drawings in which:

FIGURE 1 is a side elevation of a transport storage tank for liquids, with a portion thereof broken away in longitudinal section;

FIGURE 2 is a cross-sectional view of the tank of FIG- URE 1, taken along line IIII of FIGURE 1;

FIGURE 3 is a cross-sectional view of the tank of FIGURE 1, taken along line IIIIII of FIGURE 2;

FIGURE 4 is a cross-sectional view of the tank of FIGURE 1, taken along line IVIV of FIGURE 2; and

. FIGURE 5 is an enlarged longitudinal section of part of the tank of FIGURE 1.

Referring to FIGURE 1, a storage tank 2 is made of a number of cylindrical shell sections 4 that are Welded together and reinforced by stiffening rings 6. The tank is closed on either end by end plates 8, and bulkheads divide the tank into several compartments. Preferably all of the foregoing parts of the tank 2 are of stainless steel, because it is a high strength, relatively lightweight material, and has excellent weldability by the resistance welding process. Six longitudinal stitleners 11 in the form of steel angles are spaced equally around the inner wall of the tank 2 to increase lengthwise rigidity of the tank. The end plates 8 and bulkheads 10 are made more rigid by circular stiffeners 12, welded to the inside surfaces of the end plates and to both sides of the bulkheads. The circular shape of one of the stifleners 12 may be seen in FIGURE 2.

As shown in the broken away part of FIGURE 1, there is a network 0t cables Within the tank 2. The cables shown in this figure are only the ones which are located in one plane extending diametrically through the tank 2. They comprise primary cables 13 extending along the axis of the tank and attached to the centers of the end plates and bulkheads. Also, secondary cables 14 are connected between the longitudinal stitfeners 11 and primary cables 13. The secondary cables 14 are at an angle with the primary cables 13, being attached to the stiffeners 11 at points adjacent where the cylindrical sections 4 are joined, and to the cables 13 at nodes midway between the junctions of the sections 4. Other secondary cables 16 are connected between each longitudinal stiffener 11 and the circular stiffeners 12 on the end plates 8 and bulkheads 10.

The tank 2 actually has three times as many cables 14 and 16 as are shown in FIGURE 1, since there are additional sets of these cables, like the one shown in FIGURE 1, in two planes located 60 to either side of the plane in which the section of FIGURE 1 is taken. Some of the cables 14a and 14b in these two planes may be seen in the cross-sectional views of tank 2 in FIGURES 3 and 4.

The cables 13, 14 and 16 are all fastened so that they are held taut, and thus they serve to add rigidity to the walls and bulkheads of the tank 2. The primary cables 13 and the secondary cables 16 keep the bulkheads 10 and end plates 8 from bulging in their central areas, and thus increase the ability of these members to withstand the forward and rearward inertial forces of the liquid cargo during acceleration or deceleration of the tank.

In addition to increasing the rigidity of the walls of the tank 2, the secondary cables 14 also support a number of triangular-shaped baffle elements 18, shown in FIGURES 3 and 4. The elements 18 are connected across alternating spaces between the cables 14, and are preferably made of lightweight, high-strength stainless steel sheets having an approximate thickness of .020 inch. The edges of the sheets are wrapped around the cables 14 to hold them in place.

FIGURES 3 and 4 are cross sections of tank 2 showing adjacent conical arrays of cables 14 that are respectively convex and concave. It should be noted that the baffle elements 18 in FIGURE 4 are directly behind spaces between the baffle elements 18 of FIGURE 3.

With the bafile elements 18 arranged throughout the length of tank 2 as shown in FIGURES 3 :and 4, a great amount of turbulence is created in the liquid cargo when the tank is accelerating or decelerating. Thus, the liquid does not act as one solid body moving backward or forward between the bulkheads and end plates. Instead, each small mass of liquid behind each baflle element 18 is deflected by that element in a direction away from its original forward or rearward motion. Part of the inertial force of each of these small masses of liquid is absorbed by the resilient baflle element from which it is deflected, and the remander of its inertial force is in most cases either absorbed by the walls of the tank or counteracted by the inertial force of another mass of liquid colliding with it after being deflected in an opposite direction by another baffle element. Thus, the end plates 8 and bulkheads 10 receive very little of the total inertial force of the liquid in the tank while the tank is accelerating or decelerating.

The enlarged view of a portion of tank 2 in FIGURE 5 shows in detail how the various parts of the tank are secured to each other.

Each cylindrical shell section 4 has a flange 20 that is seam-welded at a to an adjacent flange 20 of another shell section, or an end plate 8 or bulkhead 10. A stifi'ening ring 6 is lodged between two adjacent flanges 20 and is seam-welded to each flange at b.

The longitudinal stiffening members 11 and circular stilfening members 12 are spot welded to the inner walls of the tank 2. Holes are provided in these stiifening members at appropriate places for insertion of the ends of secondary cables 14 and 16. The ends of the cables are looped through the holes and are secured in a closed loop by sleeves 22. The connections of the primary cables 13 to the end plates 8 and bulkheads 10 are accomplished by eyelets 24 welded to the centers of the end plates and bulkheads, and the ends of the cables 13 are looped through these eyelets and secured by sleeves 2 6.

The attachments of secondary cables 14 to primary cables 13 are accomplished by pairs of clamp members 28 that are bolted to opposite sides of the primary cable 13 by bolts 29. Holes 30 in each pair of clamp members 28 accommodate the ends of all the secondary cables 14, 14a and 14b to be attached to the primary cable 13 at one node. One end of each secondary cable is looped through the more convenient .hole 30 and secured in a closed loop by a sleeve 32.

While one embodiment of my invention has been shown and described herein, other adaptations and modifications will be apparent within the scope of the appended claims.

I claim:

-1. A tank for storing liquids comprising an elongated metal shell,

end plates secured to the ends of said metal shell,

a primary cable secured to said end plates and extending lengthwise through said tank,

a plurality of secondary cables connected between the inner walls of said shell and said primary cable, a group of at least two of said secondary cables connectcd to said primary cable at a common node, and each oriented at an acute angle to said primary cable,

and bafiie elements connected across alternating spaces between said secondary cables of said group to inhibit the lengthwise flow of liquid in said tank.

2. The tank of claim 1 including groups of said secondary cables arranged in conical arrays about said primary cable, the cables of one of said groups extending from a common connection with said primary cable toward one end of said tank, and the cables of another of said groups extending from a common connection with said primary cable toward the other end of said end, and

baffle elements connected between the secondary cables of each of said groups, said baffle elements connected to one of said groups of cables being placed in areas not in alignment with the baffie elements connected to said other group of cables, as viewed from the end of said tank.

3. The tank of claim 2 wherein each of said groups of secondary cables is composed of six cables, and

three of said baffle elements are connected across alternating spaces between the cables of each of said groups.

4. The tank of claim 1 including circular stiffeners mounted around the outside of said metal shell, said secondary cables being connected to said outer shell at places where said stiffening members are located.

5, The tank of claim 4 wherein said metal shell is divided into sections, said shell sections having outwardly projecting flanges on their ends, each of said flanges on a shell section being seam welded to the end flange of an adjacent shell section and each pair of flanges so joined having parallel portions spaced from one another,

and said circular stiffeners being placed in the spaces between said spaced apart portions of said flanges and seam welded to the flanges.

'6. A tank for storing liquids in transport comprising an elongated metal shell,

end plates secured to the ends of said metal shell,

at least one bulkhead mounted within said metal shell substantially parallel to said end plates, each bulkhead forming a liquid storage chamber with said shell and the adjacent bulkhead or end plate,

a primary cable extending lengthwise through each of said liquid storage chambers and secured to each bulkhead and end plate,

a plurality of secondary cables connected between the inner walls of said shell and said central cable, a group of at least two of said secondary cables located Within each of said liquid storage chambers and connected to said prim-ary cable at a common node, each of said secondary cables being oriented at an acute angle with said primary cable,

and b-aflie elements connected across alternating spaces between said secondary cables to inhibit the lengthwise fiow of liquid in each of said liquid storage chambers.

References Cited UNITED STATES PATENTS 2,009,606 7/ 1935 Diifenderfer 220-5 XR 2,296,414 9/1942 Albrecht 220-71 3,062,402 11/ 1962 Farrell 220-71 THERON E. CONDON, Primary Examiner.

GEORGE E. LOWRANCE, Examiner. 

1. A TANK FOR STORING LIQUIDS COMPRISING AN ELONGATED METAL SHELL, END PLATES SECURD TO THE ENDS OF SAID METAL SHELL, A PRIMARY CABLE SECURED TO SAID END PLATES AND EXTENDING LENGTHWISE THROUGH SAID TANK, A PLURALITY OF SECONDARY CABLES CONNECTED BETWEEN THE INNER WALLS OF SAID SHELL AND SAID PRIMARY CABLE, A GROUP OF AT LEAST TWO OF SAID SECONDARY CABLES CONNECTED TO SAID PRIMARY CABLE AT A COMMON NODE, AND EACH ORIENTED AT AN ACUTE ANGLE TO SAID PRIMARY CABLE, AND BAFFLE ELEMENTS CONNECTED ACROSS ALTERNTING SPACES BETWEEN SAID SECONDARY CABLES OF SAID GROUP TO INHIBIT THE LENGTHWISE FLOW OF LIQUID IN SAID TANK. 